Bush Tower, the landmarked but somewhat lonely neo-Gothic office building at 130 W. 42nd St., is set to join the ball on Midtown’s Cinderella block.

A joint venture of Tribeca Associates and Meadow Partners has bought a long-term leasehold on the 30-story mini-skyscraper from Marwan Dalloul’s American Properties.

Tribeca is the aggressive outfit that’s developing the Baccarat Hotel and condo tower on West 53rd Street and converting the former office building at 170 Broadway into a Marriott Residence Inn hotel.

The deal will bring new leasing energy, and a new storefront, to the 1918-vintage Bush Tower, which stands in the middle of the transformed 42nd Street south blockfront between Sixth Avenue and Broadway.

Dalloul bought it in the 1980s when Times Square was squalid and Bryant Park a shooting gallery. His company rescued the tower from oblivion, improving it with facade work, new windows and professional management. It was designated as a city landmark in 1988.

But although its 210,000 square feet are more than 80 percent leased, Bush Tower increasingly seemed an also-ran amidst glamorous projects that came to fruition during the Bloombubble.

An eyesore until recently, the block’s south side now boasts Blackstone’s 1095 Sixth Ave. with its sparkling retail “cubes” and plaza. The new Knickerbocker Hotel is set to open this winter, and curtain-wall glass has begun to appear on the Hilton Gardens Hotel next door. On the north side are the Durst Organization’s gaily lit One Bryant Park and 4 Times Square.

Terms of the Bush Tower leasehold were not released. Tribeca Associates principal Elliott Ingerman said it was structured as an upfront payment plus rent payments over time.

Dalloul had put the tower on the sale market several times, but the last offering in 2011 was yanked when it failed to draw a hoped-for $165 million.

Ingerman said plans include new lobbies, elevators and pre-built units, mostly for small tenants needing 3,000 to 5,000 square feet.

“We looked at the marketplace and found leasing velocity is 28 percent for spaces under 10,000 versus just 10 percent availability,” he said.

There will also be a new glass facade for the 42nd Street entrance. Facade changes must be approved by the Landmarks Preservation Commission. Tribeca has tapped architects Fogarty Finger to oversee the design.

Asking rents will be in the high $50s per square foot on lower floors and the $60s in the tower. CBRE’s David Hollander, Paul Walker and Christie Harle are the exclusive leasing agents.

The historic property was developed by Irving T. Bush as a display gallery for international trade passing through his company’s mammoth Bush Terminal Market in Brooklyn. Meadow Partners principal Tim Yantz called it “a sort of buried treasure we are excited to unearth, polish and reintroduce to the market.”

The deal puts Tribeca Associates in the management driver’s seat, but they regard themselves and Dalloul’s firm as partners.

“We developed a nice relationship with American Properties,” Ingerman commented.

“They had a similar vision to ours, and having someone to do the heavy lifting for them makes it easier.”